Some detail changes over the years. Loose bearings in the older versions. The snout as you said. The mounts, length and bolt patterns are the same. Some changes to the synchros, I think. But an old and a late will fit into the same place. The output shaft has the same spline count and the input as well(might be some "special" applications for non-GM applications) but over all you can use almost any year transmission in any year truck. Keep the tail casting that fits the application and off you go. The Jeep guys love the low stump gear for crawling. Was a good tough transmission.
